Method of neutralization of mahogany sulfonic acids



United ttes Patent" METHOD OF NEUTRALIZATION 0F MAHOGANY SULFONIC ACIDS Guy M. Verley, Harvey, Ill., assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine No Drawing. Application September 7, 1954 Serial No. 454,601

2 Claims. (Cl. 260-504) tions of use and form corrosive bodies, sludge, lacquer,

varnish and similar contaminants in the engines. These contaminants are known to be deleterious to efficient operation and reasonable engine life. To overcome the etfect of deterioration products, it has become a normal practice to employ detergent additives in the lubricating oil. A detergent additive appears to impart properties to the lubricating oil which enable it to retain the contaminants in suspension or dispersed in the oil so they will not settle out or adhere to the metal surfaces and result in wearing, scufiing, scoring and sticking of metal parts.

Of the numerous detergent additives known to the art, a highly eflicient group, and probably the most extensively used in commercial oils of any of the various types of detergent additives, comprises the alkaline-earth metal salts, e. g., calcium, barium, and magnesium, of mahogany sulfonic acids. While the simple neutral salts evidence detergent action, it is now recognized that basic alkalineearth metal mahogany sulfonates are more desirable than the neutral or near-neutral sulfonates because high basicity V of the sulfonate component results in greater detergency.

Mahogany sulfonic acids are commercially derived from the treatment of oils, such as lubricating oils, with fuming sulfuric acid in the manufacture of highly refined lubricating oils, medicinal oils and technical white oils. The acid treatment results in two layers; the lower layer comprising an acid sludge which is oil-insoluble and contains watersoluble green sulfonic acids is removed leaving the upper layer comprising the refined oil and the oil-soluble mahogany acids. The oil-mahogany acid solution is treated with a suitable alcohol, e. g., isopropanol, to extract the acids; the alcohol is removed by distillation and the resulting acids are then neutralized with a suitable basic material to obtain the sulfonate. Alternatively, the oilacid solution can be treated with a suitable base to produce sulfonates and the sulfonates then recovered by extraction or the like While it is common in the art to refer to the sulfonate forming step as neutralization, the usual commercial practice is to employ an excess of neutralizing agent and thereby afford a product which is highly basic. Neutralization as employed throughout this disclosure is intended to indicate reaction to the extent that a substantial amount of basic products result. The present invention is particularly concerned with such neutralization of mahogany acids.

Mahogany acids are commonly neutralized by batch methods which involve contacting the acids with a water slurry of a suitable basic material at elevated temperatures and progressively topping water from the mixture to displace the equilibrium in favor of the sulfonates. The batch methods generally are tedious, time consuming and "ice have high heat requirements. A liquid-to-liquid continuous system of neutralization has been investigated; one liquid phase was an oil solution of mahogany acids and the other phase was a liquid water solution of base. It was found that when operating under pressure at a temperature of 260 to 300 F. sulfonates of satisfactorily high basicity were obtained. There are, however, disadvantages to this continuous neutralization system 1) the final basicity is dependent on the base concentration of the water phase which must be kept so near the saturation point that any material change in temperature conditions can disrupt the process and (2) the use of sulfonates obtained by this method under normal commercial operations, i. e., in lube oils containing oxidation inhibitors such as zinc dithiophosphate and similar additives, frequently results in precipitates.

I have now discovered a method for the continuous neutralization of mahogany acids to produce sulfc-nates of high basicity. In accordance with my invention, highly basic sulfonates can be produced in a simple and eflicient manner by employing a liquid-to-solid continuous system. The essential characteristic of my invention is the use of a liquid-to-solid system in conjunction with relatively small amounts of an ionization agent. The highly basic sulfonates produced in accordance with the presentinvention are especially advantageous in that their use in lubricating blends containing additives, for example oxidation inhibitors, does not result in precipitates forming in the blend.

Sulfonates can be produced in accordance with my invention by contacting an oil-mahogany acid solution containing a small but effective amount of an ionization agent with a suitable solid phase basic material. Suitable basic materials include oxides, hydroxides and hydrated oxides and hydroxides of alkaline-earth metals such as calcium, barium and magnesium; thebariumcontaining compounds constitute the preferred basic material, and the invention will be described hereinafter in conjunction with the use of barium compounds.

Mahogany acids and the basic materials employed in this invention are articles of commerce. Mahogany acids are commonly obtained as an oil solution in the mineral oil from which they are produced. It ispreferredto employ oil solutions of the acids in the present invention, though if desired the acids can be dissolved in other solvents, such as the common hydrocarbon solvents, i. e., benzene and normally liquid aliphatic hydrocarbons. Where a solution is employed, the concentration of acids in the oil solvent is preferably about 5 to 20 volume percent. Commercial basic materials, e. g., barium oxide, are generally derived from carbonates and do, therefore, contain a minor quantity of carbonate as an impurity. The impure commercial material can be used in the present invention so long as the quantity of impurities present does not deleteriously affect the product or the efficiency of the process; normally, the quantity of impurities present in commercially obtained basic materials will not adversely affect the instant process.

In obtaining sulfo-nate products characterized by high basicity and which do not result in precipitates when used in high additive level blends of lubricating oils, I employ a small amount of an ionization agent dissolved in the hydrocarbon-mahogany acid phase. In general any ionization agent which does not react with the base under conditions of the process can be employed. Suitable agents include low molecular weight alcohols, diethyl Carbitol, -water and the like. Water is the preferred ionization agent and preferably can be used in amounts of about 0.5 to 2.0 weight percent based on the weight of liquid phase. The range of amounts of ionization agents is from about 0.5 to 5 weight percent. When using diethyl Carbitol I have found it desirable to use 2 tion is effected by passing a hydrocarbon-mahogany acid solution into contact with solid phase basic material, such as barium oxide or barium hydroxide monohydrate, to effect at least a partial neutralization of the acid oil. The solid basic material is preferably disposed as a bed of granular solids though it can be employed by slurrying in the liquid phase. An ionization agent is dissolved in the liquid phase to facilitate the neutralization. During contact of the liquid and solid phases the temperature preferably is elevated, i. e., up to about 170 F. or above; the temperature and pressure should be such that the ionization agent is not lost through vaporization. In contacting the liquid and solid phases some of the basic material normally entrains in the liquid phase so that the partially neutralized acid oil solution leaving the bed contains a small amount of fine solids suspended in it. Additional ionization agent is added and the mixture is then passed through a heating zone where the temperature is raised to about 280 to 500 F., and preferably within the range of 300 to 350 F., to facilitate substantially complete neutralization of the acids While water of reaction and vaporized ionization agent are permitted to escape. The solution is then passed into a settling zone to separate suspended solids; upon settling, the neutralized acid-oil solution is removed to a filtering zone, filtered and then topped to remove any ionization agent remaining in addition to the hydrocarbon solvent and to recover the highly basic mahogany sulfonates produced. The solids separated in the settling zone are desirably recycled to the bed of neutralization agent preferably by combining the solids with the hydrocarbon-acid feed to the bed.

It is highly desirable to employ temperatures of above about 280 F. and preferably above about 300 F. in the heating step to insure substantially complete neutralization of acids and maximum basicity of the resulting sulfonates. Higher temperatures are employed when using ionization agents such as diethyl Carbitol. Other conditions of the process can be varied widely; for example, though it is preferred to employ the solid barium compounds in finely divided state, the use of larger sizes merely extends the time necessary to produce the same effect obtained with the more finely divided material. Similarly, the use of any given flow rate through the bed of solids rather than a higher or lower fiow rate, results only in changes in the percentage of neutralization of acid obtained.

The invention will be further described by means of the. following specific examples.

Example I A mahogany acid-oil-kerosene solution of 6.7 acid number was employed in this example. It was obtained by sulfur trioxide treatment of a dewaxed Mid-Continent gas oil of about 225 SUS at 100 F. The acid oil solution containing 0.5 weight percent of added water in solution, was flowed upwardly through a 2-foot bed of barium hydroxide monohydrate standing in a column; the average fiow rate of the acid oil was 50 gaL/hour/ sq. ft. of bed. A heating coil surrounding the column supplied sufiicient heat so that the partially neutralized acid oil, which had entrained about 45 grams of finely suspended barium hydroxide monohydrate per gallon, was heated to a temperature of about F. when it left the column. Additional water, in an amount of about 0.5 weight percent, was added to the acid-oil after leaving the column; the mixture was flowed upwardly through a second column where it was heated to 300 F. to insure maximum neutralization. The mixture was then passed into the middle section of a continuous settler where the solids settled to the bottom. The overflow from the settler was filtered and then fed to a continuous topping column Where the water and hydrocabon solvent were removed from the basic barium sulfonate product. The solids collected in the settler were recycled as a slurry to the hydrocarbon-acid feed to the bed of solids. The sulfonate product was analyzed by conventional tests and found to have a base number at pH 4 of 27.4 and a percent of barium, as indicated by the sulfate ash method, of 7.18.

Example II A second run was made which was identical with Example I with the exceptions that 3 weight percent of diethyl Carbitol was employed as the ionization agent and the temperature in the heating step was about 440 F. The basic barium mahogany sulfonates resulting had a base number of 39.0 and the percent of barium, as indicated by sulfate ash, was 9.07.

I claim:

1. In a method of neutralizing mahogany sulfonic acids in the presence of water to obtain basic barium mahogany sulfonates, the improvement which comprises continuously passing a mahogany sulfonic acid-containing liquid feed stream into contact wtih a solid bed of basic barium compound in the presence of Water whereby said acids are partially neutralized, separating the resulting stream of partially neutralized acids from the bed of basic barium compound, heating said stream to a temperature above 280 F. in the presence of water and recovering the resulting basic barium mahogany sulfonates, the total amount of said water present being about 0.5 to 2 weight percent.

2. The method of claim 1 wherein said temperature is within the range of 300 to 350 F. and said barium compound is selected from the group consisting of barium oxide and barium hydroxide monohydrate.

References Cited in the file of this patent UNITED STATES PATENTS 2,395,713 Barbour Feb. 26, 1946 2,402,325 Griesinger et al June 18, 1946 7 2,417,433 McLennan Mar. 18, 1947 2,426,540 Watkins et al Aug. 26, 1947 2,573,796 Latier et al Nov. 6, 1951 

1. IN A METHOD OF NEUTRALIZING MAHOGANY SULFONIC ACIDS IN THE PRESENCE OF WATER TO OBTAIN BASIC BARIUM MAHOGANY SULFONATES, THE IMPROVEMENT WHICH COMPRISES CONTINUOUSLY PASSING A MAHOGANY SULFONIC ACID-CONTAINING LIQUID FEED STREAM INTO CONTACT WITH A SOLID BED OF BASIC BARIUM COMPOUND IN THE PRESENCE OF WATER WHEREBY SAID ACIDS ARE PARTIALLY NEUTRALIZED, SEPARATING THE RESULTING STREAM OF PARTIALLY NEUTRALIZED ACIDS FROM THE BED OF BASIC BARIUM COMPOUND, HEATING SAID STREAM TO A TEMPERATURE ABOVE 280*F. IN THE PRESENCE OF WATER AND RECOVERING THE RESULTING BASIC BARIUM MAHOGANY SULFONATES, THE TOTAL AMOUNT OF SAID WATER PRESENT BEING ABOUT 0.5 TO 2 WEIGHT PERCENT. 